func crcAppend(w WriteAheadLogger, entries [][]byte) (uint64, uint64, error) {
crc := make([]uint32, 0, len(entries))
for _, d := range entries {
crc = append(crc, crc32.ChecksumIEEE(d))
}
return w.AppendBytes(entries, crc)
}
func (c *crc32Field) check(curOffset int, buf []byte) error {
crc := crc32.ChecksumIEEE(buf[c.startOffset+4 : curOffset])
if crc != binary.BigEndian.Uint32(buf[c.startOffset:]) {
return PacketDecodingError{"CRC didn't match"}
}
return nil
}
func (s *Superblock) findByName(name InodeName, r io.ReaderAt) (int64, error) {
addr, ok := s.inodeAddr[name]
if ok {
return addr, nil
}
hash := crc32.ChecksumIEEE(name[:])
idx := int(hash) % len(s.IndirectAddr)
for tryTime := 0; tryTime < 8; tryTime++ {
offset, err := s.findAtBlock(name, r, s.IndirectAddr[idx])
if err == nil {
return offset, nil
}
if logex.Equal(err, io.EOF) {
idx++
continue
}
return 0, logex.Trace(err)
}
return 0, ErrNotFound.Trace()
}
func (c *crc32Field) run(curOffset int, buf []byte) error {
crc := crc32.ChecksumIEEE(buf[c.startOffset+4 : curOffset])
binary.BigEndian.PutUint32(buf[c.startOffset:], crc)
return nil
}
// readHeader reads the GZIP header according to section 2.3.1.
// This method does not set z.err.
func (z *Reader) readHeader() (hdr Header, err error) {
if _, err = io.ReadFull(z.r, z.buf[:10]); err != nil {
// RFC 1952, section 2.2, says the following:
// A gzip file consists of a series of "members" (compressed data sets).
//
// Other than this, the specification does not clarify whether a
// "series" is defined as "one or more" or "zero or more". To err on the
// side of caution, Go interprets this to mean "zero or more".
// Thus, it is okay to return io.EOF here.
return hdr, err
}
if z.buf[0] != gzipID1 || z.buf[1] != gzipID2 || z.buf[2] != gzipDeflate {
return hdr, ErrHeader
}
flg := z.buf[3]
hdr.ModTime = time.Unix(int64(le.Uint32(z.buf[4:8])), 0)
// z.buf[8] is XFL and is currently ignored.
hdr.OS = z.buf[9]
z.digest = crc32.ChecksumIEEE(z.buf[:10])
if flg&flagExtra != 0 {
if _, err = io.ReadFull(z.r, z.buf[:2]); err != nil {
return hdr, noEOF(err)
}
z.digest = crc32.Update(z.digest, crc32.IEEETable, z.buf[:2])
data := make([]byte, le.Uint16(z.buf[:2]))
if _, err = io.ReadFull(z.r, data); err != nil {
return hdr, noEOF(err)
}
z.digest = crc32.Update(z.digest, crc32.IEEETable, data)
hdr.Extra = data
}
var s string
if flg&flagName != 0 {
if s, err = z.readString(); err != nil {
return hdr, err
}
hdr.Name = s
}
if flg&flagComment != 0 {
if s, err = z.readString(); err != nil {
return hdr, err
}
hdr.Comment = s
}
if flg&flagHdrCrc != 0 {
if _, err = io.ReadFull(z.r, z.buf[:2]); err != nil {
return hdr, noEOF(err)
}
digest := le.Uint16(z.buf[:2])
if digest != uint16(z.digest) {
return hdr, ErrHeader
}
}
z.digest = 0
if z.decompressor == nil {
z.decompressor = flate.NewReader(z.r)
} else {
z.decompressor.(flate.Resetter).Reset(z.r, nil)
}
return hdr, nil
}
